7S6 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



method of diagnosis has been found to be much more valuable than the 

 bacteriological examination of eggs. 



Eradication of infected laying stock is the' solution of the white 

 diarrhoea problem. Flocks which are at all doubtful, or which have 

 given a history of infection, should be tested, and the reacting fowls 

 eliminated. Better still, no eggs should be used for hatching which 

 have come from flocks that have shown an appreciable degree of infec- 

 tion, although reacting individuals have been removed. 



Chicken Cholera* 



Bacterium cholera galUnarwn 



The bacterium causing this disease was first noticed by Perroncito 

 and Toussaint; later, in 1880, it was described by Pasteur, and was the 

 first organism in which the French savant succeeded in attenuating the 

 virulence and the first disease for which a vaccine made from atten- 

 uated organisms was prepared. Koch in 1878 described an organism 

 of similar pathogenicity as the bacterium of rabbit septicaemia and in 

 1886 the term hemorrhagic septictemia was given by Hueppe to a num- 

 ber of infectious diseases of the lower animals in which hemorrhagic 

 spots were found in the tissues and internal organs. In 1900 Lignieres 

 discussed these bacteria, and named them as a genus, Pasteurellose, the 

 specific name given depending on the animal for which it was most 

 pathogenic. Thus he distinguished avian, porcine, ovine, bovine, 

 equine and canine Pasteurelloses. 



The specific characters of this group are small ovoid bacteria, often showing bi- 

 polar staining when treated with the aniline dyes, non-motile, no spores, Gram- 

 negative, polymorphic, not liquefying gelatin, no visible growth on naturally acid 

 potato, milk unchanged, no indol production, generally aerobic but also a facultative 

 anaerobe, virulence changeable, but usually very pronounced. . 



The bacterium of fowl cholera, Bad. cholera gallinarum, or avian Pasteurellose, is 

 from o.Sa* to i.2Sm long and 0.25^ to 0.40/11 broad. It develops best at 37°, and very 

 slowly at 20°. It loses its virulence in cultures very quickly, and it succumbs 

 readily to desiccation. 



The disease is of frequent occurrence in Europe, but not often seen 

 in North America but some outbreaks have been reported in the United 

 States and Canada. Unfortunately it has been confused by poultry- 



* Prepared by F. C. Harrison. 



